The present invention is related to a marker lamp for vehicles, more particularly, a marker lamp that does not require the use of mirrors or reflectors to distribute light.
Marker lights are an important factor in the safe operation of vehicles, especially trucks. Marker lights must be easily recognized and must be well defined in terms of A color, light intensity and light distribution. A marker lamp will be used along side of a vehicle to indicate the overall shape, length and width of a vehicle. To accomplish this, the marker lamp must distribute light over a wide range.
Marker lamps have been made by high power consuming incandescent bulbs, light emitting diodes and the use of reflective surfaces (mirrors) to get a wide range of light diffusion. Another design of marker apparatus exists, a reflector, whose construction allows the lamp to reflect the light beam emitted from an automobile. These types of markers are usually used on the side of the road so that a driver can recognized the road boundary. The design of this type of marker is limited since the efficiency of recognition depends on the intensity of the light beam produced by oncoming vehicles. A vehicle without headlamps, for example, will not produce light that may be reflected. Combination marker/clearance lamps that are made by using light-emitting diodes exist. The advantage of using light-emitting diodes in lamps is that a light emitting diode has a relatively long service life and low power requirements. Most of the other designs require a large number of light-emitting diodes and complicated optics to allow the correct light intensity and distribution. Large numbers of light-emitting diodes produce additional heat, which must be removed from the lamp, since heat will affect the performance of the light emitting diodes. Thus, heat dissipation elements must be added and these elements complicate the design of the lamps. To obtain the proper light distribution, the other designs require the use of reflective surfaces (usually mirrors), or segmented circuit boards to which are mounted light-emitting diodes to provide for different light distribution, or aimed light-emitting diodes. Reflective surfaces or mirrors add additional cost to the design and at least one extra part to the lamp design. Segmented boards, on the other hand, require special mounting considerations and generally can not be potted for protection. This makes the construction of the lamp using segment circuit boards more complicated and potentially more fragile.
In addition to the above limitations, other designs of marker lamps do not meet both the United States (and the Society of Automotive Engineers) and European standards for marker lamps. Also, other designs of marker lamps do not allow both horizontal and vertical mounting while continuing to meet the U.S. and European standards. The United States standards are usually less stringent than the Society of Automotive Engineers (xe2x80x9cSAExe2x80x9d) standards. Thus, the SAE standards require that marker lamps produce a light intensity of 0.25 cd for a red colored lamp and 0.62 cd for an amber colored lamp over a range of 45 degrees in each direction from a reference axis. The United Nations (U.N.) standards for the European Community require that marker lamps produce a minimum light intensity of 4.0 cd (in the axis of reference) and 0.6 cd within the specific angular field. The U.N. standards require that marker lamps have a maximum light intensity of 25.0 cd. The U.N. standards require a vertical light distribution over at least 10 degrees in each direction from a reference axis in the center of the lamp. The U.N. standards require a horizontal distribution over at least 30 degrees in each direction from a reference axis in the center of the lamp.
U.S. Pat. No. 5,388,035 shows a circular marker lamp using only three light-emitting diodes. Each of the light-emitting diodes is aimed at a specific angle so that the conical light output beam is centered on.an axis that is normal to the plane of the lens wall. The rear surface of the lens front wall contains three different sets of light spreading prism ribs, which need to be optically aligned with each light-emitting diode.
U.S. Pat. No. 1,530,621 teaches the use of a conical reflector as part of an optical system to direct light towards a single spot as used in a light projector.
U.S. Pat. No. 2,254,961 discloses the use of a unitary lens, light and reflector system in which an outwardly curved portion (bubble shape) is present in the center of the lens.
U.S. Pat. No. 3,633,022 is generally directed to a lamp having a lens, a light source, and a reflector. The lens has an outer surface that acts as a dispersing lens. This dispersing element is form by a double concave cylindrical lens with a double grooved shape. The design is directed to an incandescent lamp, which uses reflectors to accomplish the desired spread and intensity of light.
Finally, U.S. Pat. No. 5,580,156 illustrates a marker apparatus for traffic capable of improving the recognition efficiency by using the enhancing effect of a light source beam and a reflected light beam. The marker apparatus is used at road boundaries to help drivers recognize the boundaries of the road. The marker apparatus accomplishes this by the use of a retroreflector which is composed of three reflective surfaces arranged on three surfaces of a trigonal pyramid and a light source disposed on an optical axis of the retroreflector. A disadvantage of this design it is slightly bulky with more than three light-emitting diodes required.
The present invention solves the above mentioned limitations of the previous designs in a cost-effective manner by using a reduced number of light-emitting diodes and an optics design. The invention utilizes a housing, a lens, power cables, a circuit board, light emitting diodes and an optics design incorporated into- the lens. The invention also uses seals, resistors, and cables such that power is supplied to the marker lamp and the lamp can be assimilated into the overall vehicle power system. The optics design does not require a mirror to produce the light intensity and angular distribution required by the United States and by the United Nations standards for the European Community for marker lamps. The resultant lamp will be a marker lamp that is sturdy, slim, and reasonably priced. The resultant lamp can also be mounted either horizontally or vertically as respects the long axis of the lamp, while still meeting the aforementioned standards.
The present invention uses a combination of corner cube optics and intersecting cylindrical prisms or picture frame optics in the lens of the lamp. This corner cube optics is also known as retrodirective reflectors or reflex reflectors. The reflex reflectors at each side of the lens of the marker lamp efficiently reflects light from outside sources such as an incoming car, or a roadside traffic lamp, or the sun. The center portion of the lens of the marker lamp is formed by a series of cylindrical prisms intersecting each other, in such a way to resemble the appearance of a picture frame. The center portion could also be modified from the present description with a simple convex lens. The function of the center portion of the lens is to concentrate the light from the light emitting diodes and distribute the light over the desired parameters.
These above mentioned characteristics and other objects of the invention will become more apparent from the following description of the preferred embodiments.
Accordingly, it is an object of the present invention to provide a marker lamp that utilizes a reduced number of light emitting diodes.
It is also an object of the present invention to provide a unique optical system, including reflective surfaces at the sides and cylindrical prisms in the center.
It is a further object of the present invention to provide a unique optical system that distributes light over a wide range of angles.
In addition, it is an object of the present invention to provide a marker lamp comporting with the requirements of both the United States and United Nations standards for the European Community for marker lamps.
Additionally, it is an object of the present invention to provide a marker lamp that can be mounted either horizontally or vertically along the long axis of the lamp while continuing to meet both the U.S. and U.N. standards.